Since its first introduction, the method of playing golf, playing equipment, and playing rules have been refined to a great degree. One area of refinement has been in the development of specific postural positioning, such as in the development of stances and grips, in order to increase the effectiveness of the golf swing. Postural positioning may vary in accordance with a selected club being used, the distance in which the ball is to be driven, and the playing environment.
To successfully master the art of playing golf, one must be proficient in initially driving the ball off the tee, positioning the ball on the green, and putting the ball into the hole. Normally, a wood is used for driving the ball, a putter is used for putting the ball, and an iron is used for most intermediate strokes required to position the ball on the green. A myriad of wood and iron clubs have been developed in order to provide for a relatively fine adjustment of the strokes to be achieved.
A given set of golf clubs includes a plurality of numbered wood and iron clubs as well as a pitching wedge, a sand wedge and a putter. The wood clubs may range in number from one to seven and the irons typically range in number from one to nine. Each club includes shaft and a head defining a face. The lower numbered clubs have longer shafts and the higher numbered clubs have shorter shafts. The face of each club is inclined rearwardly to the vertical axis of the shaft in a direction of the movement of the head of the club when being swung. The value of the angle of the face with respect to the vertical axis of the shaft, that is, the loft angle, increases with an increase in the number of the club or as the shaft length decreases, the sand wedge having the highest loft angle value. The smaller the loft angle, the lower the loft of the ball and the greater the run of the ball after subsequent contact with the ground.
For any set of golf clubs, it is important that the swing of each club be consistent. However, even when golf clubs are swung consistently, the loft changes at impact due to centrifugal forces. Prior art teaches that this tendency to change the loft can be compensated for by providing a set of golf clubs which have progressively decreasing offsets, beginning with the lower numbered clubs and progressively decreasing toward the higher numbered clubs. The offset is the distance between the central axis of the club shaft and the bottom leading edge of the club face. For the most part, the leading edge of the club face actually trails the shaft axis of the clubs having longer shafts and the leading edge of the club face actually proceeds the shaft axis of the clubs having shorter shafts. The offset is related to the distance by which the center of the mass of the club head trails the axis of the shaft. Because of the offset and the related position of the center of mass, the centrifugal forces that result about the center of mass of the head, when the club is swung, tend to cause the club to increase its loft angle as the shaft bends. By progressively varying the offset from the lower numbered clubs to the higher numbered clubs, an appropriate degree of consistent loft change can be achieved from club to club.
Golf club sets having clubs with offset club faces are well known in the prior art. For example, U.S. Pat. No. 3,966,210, issued Jun. 29, 1976 to John J. Rozmus, shows two distinct golf club heads each having an offset club face. The leading edge of the ball striking face of each club head is offset so as to precede the vertical axis of the shaft in a direction of the movement of the head of the club when being swung. A set of golf club irons is shown in U.S. Pat. No. 4,854,581, issued Aug. 8, 1989 to D. Clayton Long. Long discloses a set of progressively decreasing offsets between the axis of the club shaft and the center of mass projected to the horizontal plane beginning with the lower numbered irons having longer shafts and progressing to the higher numbered irons having shorter shafts. Another iron golf club set is shown in U.S. Pat. No. 4,986,541, issued Jan. 22, 1991 to Mitsutake Teramoto et al., wherein the set comprises a plurality of iron clubs having different loft angles between the face of the golf club head and the axis of the shaft of the club. At least some of the clubs in the set have face progression values which are reduced consecutively or in steps in accordance with a decrease in the number of the iron or a decrease in the value of the loft angle. Yet another set of iron clubs is shown in UK Patent Application GB 2 194 737 A, published Mar. 16, 1988 to Masashi Kobayashi, wherein the offset between the leading edge of the golf club face and the leading edge of the golf club shaft is increased as the length of the club shaft increase so as to delay the impact of the club face with the golf ball enabling the player to more easily achieve a timely impact of the golf club face with the ball.
All of the problems associated with achieving a timely impact of the golf club with the ball have yet to be addressed. A golf club set which offers a variation in face progression values including face progression plus values, zero values, and minus values would meet the needs to achieving a timely impact of the golf club with the ball. Applicant proposes a golf club set having such a variation in face progression values. None of the above noted patents, either singly or in combination, are seen to disclose the specific arrangement of concepts disclosed by applicant with respect to the present invention.